lib/libthread_xu/thread/thr_pspinlock.c

   1 /*-
   2  * Copyright (c) 2003 David Xu <davidxu@freebsd.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  */
  27
  28 #include "namespace.h"
  29 #include <machine/tls.h>
  30 #include <errno.h>
  31 #include <stdlib.h>
  32 #include <pthread.h>
  33 #include <pthread_np.h>
  34 #include "un-namespace.h"
  35
  36 #include "thr_private.h"
  37
  38 #define SPIN_COUNT 100000
  39
  40 int
  41 _pthread_spin_init(pthread_spinlock_t *lock, int pshared)
  42 {
  43         pthread_spinlock_t lck;
  44
  45         if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE)
  46                 return (EINVAL);
  47         lck = __malloc(sizeof(struct __pthread_spinlock_s));
  48         if (lck == NULL)
  49                 return (ENOMEM);
  50         _thr_umtx_init(&lck->s_lock);
  51         *lock = lck;
  52
  53         return (0);
  54 }
  55
  56 int
  57 _pthread_spin_destroy(pthread_spinlock_t *lock)
  58 {
  59         int ret;
  60
  61         if (lock == NULL || *lock == NULL) {
  62                 ret = EINVAL;
  63         } else {
  64                 __free(*lock);
  65                 *lock = NULL;
  66                 ret = 0;
  67         }
  68
  69         return (ret);
  70 }
  71
  72 int
  73 _pthread_spin_trylock(pthread_spinlock_t *lock)
  74 {
  75         pthread_t curthread = tls_get_curthread();
  76         pthread_spinlock_t lck;
  77
  78         if (lock == NULL || (lck = *lock) == NULL)
  79                 return (EINVAL);
  80         return (THR_UMTX_TRYLOCK_PERSIST(curthread, &lck->s_lock));
  81 }
  82
  83 int
  84 _pthread_spin_lock(pthread_spinlock_t *lock)
  85 {
  86         pthread_t curthread;
  87         pthread_spinlock_t lck;
  88         int count;
  89
  90         if (lock == NULL || (lck = *lock) == NULL)
  91                 return (EINVAL);
  92
  93         curthread = tls_get_curthread();
  94         count = SPIN_COUNT;
  95         while (THR_UMTX_TRYLOCK_PERSIST(curthread, &lck->s_lock) != 0) {
  96                 while (lck->s_lock) {
  97                         CPU_SPINWAIT;   /* tell cpu we are spinning */
  98                         if (--count <= 0) {
  99                                 count = SPIN_COUNT;
 100                                 _pthread_yield();
 101                         }
 102                 }
 103         }
 104         return (0);
 105 }
 106
 107 int
 108 _pthread_spin_unlock(pthread_spinlock_t *lock)
 109 {
 110         pthread_t curthread = tls_get_curthread();
 111         pthread_spinlock_t lck;
 112
 113         if (lock == NULL || (lck = *lock) == NULL)
 114                 return (EINVAL);
 115         /* XXX: shouldn't return status? */
 116         THR_UMTX_UNLOCK_PERSIST(curthread, &lck->s_lock);
 117         return (0);
 118 }
 119
 120 __strong_reference(_pthread_spin_init, pthread_spin_init);
 121 __strong_reference(_pthread_spin_destroy, pthread_spin_destroy);
 122 __strong_reference(_pthread_spin_trylock, pthread_spin_trylock);
 123 __strong_reference(_pthread_spin_lock, pthread_spin_lock);
 124 __strong_reference(_pthread_spin_unlock, pthread_spin_unlock);